As the number of oil and gas wells completed in sensitive environments has increased so has the need to provide a dependable shutoff valve, for use in subsurface well tubing and in other critical locations, and to provide for adequate testing of such a valve, to make more certain that it will close when required to do so in an emergency.
The present invention is directed to a subsurface shutoff valve in the form of a sleeve and control means, which is summarized in the following objects:
First, to provide a sleeve type of shutoff valve the sleeve of which provides, when open, an unobstructed flow passage of maximum internal diameter for a given external sleeve diameter and is surrounded by a peripheral control chamber which, when pressurized, causes the valve to effect a full seal;
Second, to provide a sleeve type shutoff valve the sleeve of which is formed of readily deformable elastomeric material and is provided with novel reinforcing so arranged that, when subjected to external pressure to close the valve, the reinforcing limits axial displacement of the elastomeric material even when the valve is subjected to an extreme pressure differential between its ends.
Third, to provide a shutoff valve, as indicated in the preceding objects, and control means therefore embodying a pressure-fluid reservoir as well as novelly arranged control valves connected to the surface through control and vent lines.
Fourth, to provide a shutoff valve and control means, as indicated in the preceding objects, in which the control means causes the shutoff valve to close automatically in the event of either surface damage at the wellhead that ruptures the control line or the development of a leak in the control line.
Fifth, to provide a shutoff valve and control means, as indicated in the other objects, whereby at regular intervals or at any other time the high-pressure reservoir can be checked for adequate pressure and if necessary replenished from a reserve surface supply of high-pressure fluid.
Sixth, to provide a shutoff valve and control means whereby the shutoff valve may be operated manually from the surface.